Carbothermal reduction synthesis of high porosity and low thermal conductivity ZrC-SiC ceramics via an one-step sintering technique

In this work, porous ZrC-SiC ceramics with high porosity and low thermal conductivity were successfully prepared using zircon (ZrSiO4) and carbon black as material precursors via a facile one-step sintering approach combining in-situ carbothermal reduction reaction (at 1600 degrees C for 2 h) and partial hot-pressing sintering technique (at 1900 degrees C for 1 h). Carbon black not only served as a reducing agent, but also performed as a pore-foaming agent for synthesizing porous ZrC-SiC ceramics. The prepared porous ZrC-SiC ceramics with homogeneous microstructure (with grain size in the 50-1000 nm range and pore size in the 0.2-4 mu m range) possessed high porosity of 61.37-70.78%, relatively high compressive strength of 1.31-7.48 MPa, and low room temperature thermal conductivity of 1.48-4.90 W.m(-1)K(-1). The fabricated porous ZrC-SiC ceramics with higher strength and lower thermal conductivity can be used as a promising light-weight thermal insulation material.